Preparing drug solutions and suspensions for animal studies is a core skill for B.Pharm students, combining formulation science, pharmacology, and lab technique. This topic covers dose calculation, vehicle selection, sterilization, pH and osmolarity adjustment, suspending agents, particle size control, wetting agents, and stability testing to ensure safe, effective dosing in preclinical models. Students learn compounding procedures, aseptic technique, analytical quality control, and regulatory considerations such as labeling and storage. Practical understanding of flocculation, sedimentation volume, viscosity modification, and compatibility of excipients is essential for reproducible animal studies. These skills directly impact data reliability, animal welfare, and translational relevance of pharmacological findings. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What distinguishes a suspension from a solution in animal dosing formulations?
- Drug molecules are completely dissolved in a solution
- Suspension contains dispersed insoluble particles in a liquid medium
- Solutions always contain larger particles than suspensions
- Suspensions are clear while solutions are cloudy
Correct Answer: Suspension contains dispersed insoluble particles in a liquid medium
Q2. Which vehicle is most appropriate for preparing sterile parenteral drug solutions for animal studies?
- Purified water for oral use
- Sterile water for injection
- Physiological buffer without sterilization
- Non-sterile normal saline from pharmacy stock
Correct Answer: Sterile water for injection
Q3. What is the primary role of a wetting agent in a suspension formulation?
- To increase the pH of the medium
- To improve powder wetting and dispersion in the vehicle
- To act as a preservative against microbes
- To increase viscosity and prevent flow
Correct Answer: To improve powder wetting and dispersion in the vehicle
Q4. How is sedimentation volume (F) defined for suspensions?
- Ratio of initial sediment volume to final sediment volume
- Final sediment volume divided by original total volume (Vf/Vo)
- Total volume minus sediment volume
- Volume of supernatant divided by sediment volume
Correct Answer: Final sediment volume divided by original total volume (Vf/Vo)
Q5. What is an advantage of a flocculated suspension in animal dosing?
- They form a hard cake that is difficult to re-disperse
- They display loose aggregates that are easily redispersed
- They never settle during storage
- They eliminate the need for suspending agents
Correct Answer: They display loose aggregates that are easily redispersed
Q6. Which of the following is a commonly used suspending agent in oral suspensions for rodents?
- Polyethylene glycol 400 (PEG 400)
- Xanthan gum
- Sodium chloride
- Benzyl alcohol
Correct Answer: Xanthan gum
Q7. How does reducing particle size of a drug powder generally affect its dissolution rate in a suspension?
- It decreases dissolution rate due to aggregation
- It increases dissolution rate by increasing surface area
- It has no effect on dissolution rate
- It always makes the drug insoluble
Correct Answer: It increases dissolution rate by increasing surface area
Q8. What does zeta potential indicate in colloidal suspensions used for animal studies?
- The viscosity of the suspension
- Electrical potential at the slipping plane indicating repulsive forces
- The solubility of the active drug
- The pH value of the suspension
Correct Answer: Electrical potential at the slipping plane indicating repulsive forces
Q9. Which phenomenon involves smaller particles dissolving and redepositing on larger particles, destabilizing suspensions?
- Flocculation
- Ostwald ripening
- Coagulation by pH change
- Emulsification
Correct Answer: Ostwald ripening
Q10. Which excipient is a nonionic surfactant commonly used to improve wetting and dispersion of powders?
- Sodium lauryl sulfate
- Polysorbate 80 (Tween 80)
- Hydrochloric acid
- Calcium carbonate
Correct Answer: Polysorbate 80 (Tween 80)
Q11. For heat-stable parenteral solutions intended for animal use, which sterilization method is appropriate?
- Autoclaving at 121°C for an appropriate time
- Dry heat at 60°C for 10 minutes
- Room temperature filtration only
- Ultrasonic agitation
Correct Answer: Autoclaving at 121°C for an appropriate time
Q12. What pore size membrane filter is typically used for terminal sterilization of aqueous solutions by filtration?
- 5.0 µm
- 0.45 µm
- 0.22 µm
- 10 µm
Correct Answer: 0.22 µm
Q13. Which preservative is commonly used in multidose aqueous parenteral formulations for animals?
- Benzyl alcohol
- Sodium bicarbonate
- Magnesium stearate
- Citric acid only
Correct Answer: Benzyl alcohol
Q14. Why is pH adjustment important in preparing drug solutions for animal studies?
- It only affects color but not stability
- To maintain drug solubility, chemical stability, and compatibility
- pH is irrelevant if preservatives are used
- To increase the particle size of the drug
Correct Answer: To maintain drug solubility, chemical stability, and compatibility
Q15. What is the approximate isotonicity target for parenteral solutions used in small animals?
- 50 mOsm/L
- 150 mOsm/L
- Approximately 300 mOsm/L (0.9% NaCl)
- 600 mOsm/L
Correct Answer: Approximately 300 mOsm/L (0.9% NaCl)
Q16. Which practice is recommended when reconstituting a powdered suspension for animal dosing?
- Vigorous shaking to produce foam
- Gentle inversion and mixing to avoid foaming
- Heating to 80°C to dissolve particles
- Adding organic solvents to increase solubility
Correct Answer: Gentle inversion and mixing to avoid foaming
Q17. Which method is commonly used to scale dosing between species for preclinical studies?
- Linear scaling by body weight without adjustments
- Allometric scaling based on body surface area
- Scaling by age only
- Using human dose directly for animals
Correct Answer: Allometric scaling based on body surface area
Q18. When is the intraperitoneal (IP) route commonly used in rodent studies?
- When topical delivery is required
- For systemic administration when IV access is difficult
- Only for administering oils
- To target the central nervous system directly
Correct Answer: For systemic administration when IV access is difficult
Q19. Which analytical method is considered stability-indicating for detecting drug degradation in solutions?
- Visual inspection only
- HPLC assay that separates drug and degradation products
- pH paper test alone
- Simple UV absorbance without separation
Correct Answer: HPLC assay that separates drug and degradation products
Q20. What is the role of chelating agents such as EDTA in aqueous formulations for animal studies?
- To act as primary suspending agents
- To complex metal ions and reduce oxidation
- To lower the freezing point
- To increase particle size
Correct Answer: To complex metal ions and reduce oxidation
Q21. According to Stoke’s law, how does increasing the viscosity of the medium affect sedimentation rate of particles?
- Increases sedimentation rate
- Has no effect on sedimentation rate
- Decreases sedimentation rate
- Causes immediate dissolution
Correct Answer: Decreases sedimentation rate
Q22. After reconstitution, how should many aqueous suspensions for animal dosing be stored?
- At room temperature indefinitely
- Frozen at -80°C
- Refrigerated and used within the labeled time
- Exposed to light to ensure sterility
Correct Answer: Refrigerated and used within the labeled time
Q23. Which term describes formation of loosely bound aggregates that settle rapidly but are easily redispersed?
- Caking
- Flocculation
- Coagulation causing irreversible clumping
- Osmotic burst
Correct Answer: Flocculation
Q24. Which test best assesses uniformity of a suspension intended for animal dosing?
- Measuring pH only
- Assaying aliquots for drug content after mixing
- Observing color change visually
- Measuring viscosity at 1000 rpm only
Correct Answer: Assaying aliquots for drug content after mixing
Q25. What is the primary function of wetting agents in solid-in-liquid suspensions?
- To increase ionic strength of the medium
- To reduce interfacial tension between particles and medium
- To act as antimicrobial preservatives
- To neutralize the drug
Correct Answer: To reduce interfacial tension between particles and medium
Q26. Which excipient class is specifically used to prevent hard caking of sediment in suspensions?
- Buffers
- Flocculating agents
- Colorants
- Sweeteners
Correct Answer: Flocculating agents
Q27. What fundamental difference separates an emulsion from a suspension?
- An emulsion is solid dispersed in liquid; a suspension is liquid in liquid
- An emulsion contains two immiscible liquids; a suspension contains solid particles in a liquid
- Emulsions never require emulsifiers while suspensions always do
- Suspensions are chemically bonded systems, emulsions are not
Correct Answer: An emulsion contains two immiscible liquids; a suspension contains solid particles in a liquid
Q28. Why must formulations for intrathecal administration in animal studies be pyrogen-free and sterile?
- Because intrathecal injections are applied topically
- Because they are administered into cerebrospinal fluid and require strict sterility for safety
- Because pyrogens improve drug absorption in the CNS
- Because sterility is irrelevant for intrathecal routes
Correct Answer: Because they are administered into cerebrospinal fluid and require strict sterility for safety
Q29. How do surfactants contribute to stability of suspensions?
- By increasing particle density
- By reducing interfacial tension and aiding wetting and dispersion
- By inducing crystallization of the drug
- By neutralizing buffer capacity
Correct Answer: By reducing interfacial tension and aiding wetting and dispersion
Q30. Which combination of quality control parameters best monitors physical stability of a suspension for animal studies?
- Particle size distribution and sedimentation volume monitoring
- Only visual color check
- Only pH measurement
- Only osmolality measurement
Correct Answer: Particle size distribution and sedimentation volume monitoring
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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